2 00:00:10,330 --> 00:00:14,090 Winston Churchill once said of the Americans, that we can be counted 3 00:00:14,090 --> 00:00:17,780 on to do the right thing, after we've exhausted all the alternatives. 4 00:00:17,780 --> 00:00:21,880 What are the alternatives to actually cutting our Co2 emissions? 5 00:00:21,880 --> 00:00:23,910 Generally, they're called geoengineering, 6 00:00:23,910 --> 00:00:27,950 based on the idea that we are now powerful 7 00:00:27,950 --> 00:00:31,950 enough that we can actually engineer the planet in some ways. 8 00:00:31,950 --> 00:00:35,080 There are different strategies that are all called geoengineering. 9 00:00:35,080 --> 00:00:35,750 They're very different, 10 00:00:35,750 --> 00:00:40,370 and have possibilities to actually work. 11 00:00:40,370 --> 00:00:45,160 One way that would work 12 00:00:45,160 --> 00:00:50,260 to solve the climate problem, and is my hope 13 00:00:50,260 --> 00:00:55,530 for the future, is to actually eventually 14 00:00:55,530 --> 00:01:01,450 scrub CO2 from the atmosphere. This could be done. 15 00:01:01,450 --> 00:01:06,430 CO2 reacts with a base to make bicarbonate. You saw this 16 00:01:06,430 --> 00:01:11,320 using carbonate ion a base in the seawater chemistry, 17 00:01:11,320 --> 00:01:15,370 this is the buffer mechanism whereby seawater can hold 18 00:01:15,370 --> 00:01:20,850 more CO2 than it would if it didn't have that chemistry. 19 00:01:20,850 --> 00:01:23,730 It can be used in an industrial way, too; 20 00:01:23,730 --> 00:01:27,330 the base that they usually talk 21 00:01:27,330 --> 00:01:33,020 about is called an amine. But it functions in the same way. 22 00:01:33,020 --> 00:01:38,670 You run the CO2 through a solution of this, and it turns into bicarbonate, 23 00:01:38,670 --> 00:01:42,820 and then you have to get the CO2 back off again, 24 00:01:42,820 --> 00:01:48,370 and do something with it. This is how they scrub 25 00:01:48,370 --> 00:01:53,180 CO2 from the air in submarines, 26 00:01:54,360 --> 00:01:59,760 and it's also how they scrub sulfur dioxide 27 00:01:59,760 --> 00:02:06,180 from coal power plants. It's not a novel process. 28 00:02:06,180 --> 00:02:09,780 Once you've captured the CO2 then you have to figure out what to do with it. 29 00:02:09,780 --> 00:02:14,120 The name they use for this is CO2 sequestration. 30 00:02:14,120 --> 00:02:19,040 There are two basic options: on land and in the ocean. 31 00:02:19,040 --> 00:02:25,460 On land, there are deposits, like layers of sandstone, 33 00:02:25,460 --> 00:02:28,150 with coarse enough grains that fluid in between 34 00:02:28,150 --> 00:02:31,130 can flow around, and 35 00:02:31,130 --> 00:02:34,440 deep enough that the water is salty. 36 00:02:34,440 --> 00:02:37,640 They call these saline aquifers. 37 00:02:37,640 --> 00:02:40,180 Since the water is salty, nobody wants it, 38 00:02:40,180 --> 00:02:45,330 might as well put some CO2 in it. It turns out that there is capacity for 39 00:02:45,330 --> 00:02:50,650 thousands of gigatons of carbon in these sorts of deposits in the earth. 40 00:02:50,650 --> 00:02:53,030 They're not evenly spread out around the earth. 41 00:02:53,030 --> 00:02:55,650 We have lots of them in the United States. 42 00:02:55,650 --> 00:02:58,470 There are no such deposits in Japan, for example. 43 00:03:00,480 --> 00:03:06,440 The CO2 at this pressure is actually a liquid, rather than a gas, 44 00:03:06,440 --> 00:03:11,765 and it eventually reacts with the CaO compoenen 45 00:03:11,765 --> 00:03:13,650 of rocks that are down there. 46 00:03:13,650 --> 00:03:16,220 That's the Urey reaction again. 47 00:03:16,220 --> 00:03:18,470 We pump the CO2 down there and it can 48 00:03:18,470 --> 00:03:22,190 react with igneous rocks, which neutralizes it. 49 00:03:22,190 --> 00:03:25,560 The other option that people talk about is to inject it 50 00:03:25,560 --> 00:03:26,800 in the ocean. 51 00:03:26,800 --> 00:03:32,560 Here is a ship and a pipe and a bubbler and you bubble some CO2 out and 52 00:03:32,560 --> 00:03:36,670 and it floats up, it would be liquid in that case, but it would float. 53 00:03:37,980 --> 00:03:40,080 well, it actually depends on the depth in the ocean. 54 00:03:40,080 --> 00:03:41,640 At some depth, the CO2 is more 55 00:03:41,640 --> 00:03:44,470 compressible than water, so it would actually sink. 56 00:03:44,470 --> 00:03:47,470 But either way, it would eventually dissolve in the water. 57 00:03:48,490 --> 00:03:50,680 And once that happens, 58 00:03:50,680 --> 00:03:52,866 the CO2 dissolving in the deep ocean, it 59 00:03:52,866 --> 00:03:57,780 would exchange with the atmosphere, on a time scale 60 00:03:57,780 --> 00:04:03,690 of about 1000 years, just the same as if we had put it in the atmosphere. 61 00:04:03,690 --> 00:04:07,920 It would take 1000 years to equilibrate with the ocean, then you'd add this long tail. 62 00:04:07,920 --> 00:04:09,080 You put it in the ocean, it would 63 00:04:09,080 --> 00:04:12,260 take 1000 years to equilibrate with the atmosphere. 64 00:04:12,260 --> 00:04:15,820 This process would eliminate the peak, 65 00:04:15,820 --> 00:04:17,780 but it wouldn't eliminate the long tail. 66 00:04:17,780 --> 00:04:22,930 It would only be a partial solution to what to do with the CO2. 67 00:04:26,660 --> 00:04:31,330 Another idea that you hear about, which I am personally not a believer in, is to 68 00:04:31,330 --> 00:04:36,440 fertilize the ocean. It is found that in 69 00:04:36,440 --> 00:04:41,370 large sections of the surface ocean, phytoplankton growth 70 00:04:41,370 --> 00:04:46,165 is limited by needing trace amounts of iron, Fe. 71 00:04:46,165 --> 00:04:54,920 There are those who propose putting 73 00:04:54,920 --> 00:04:58,150 iron in the ocean, making the phytoplankton grow. 74 00:04:58,150 --> 00:05:01,320 These dead phytoplankton will sink in the ocean, 75 00:05:01,320 --> 00:05:05,560 pull CO2 out of the surface ocean water. 76 00:05:05,560 --> 00:05:09,160 This is a very strong lever because, you only 77 00:05:09,160 --> 00:05:13,570 need one atom of iron for maybe 20,000 atoms of CO2. 78 00:05:13,570 --> 00:05:16,380 It seems like a very powerful technique. 79 00:05:16,380 --> 00:05:18,180 The problem is that the CO2 80 00:05:18,180 --> 00:05:21,620 in the atmosphere only exchanges with that from the 81 00:05:21,620 --> 00:05:25,070 ocean in, like we've said, about a thousand years. 82 00:05:25,070 --> 00:05:26,880 If you could fertilize the ocean for 83 00:05:26,880 --> 00:05:29,010 a thousand years, you would start to get somewhere. 84 00:05:29,010 --> 00:05:36,230 But in simulations of what happens if you just fertilize 85 00:05:37,230 --> 00:05:43,350 in one spot in the ocean, for a few decades, it's found that the impact on 86 00:05:43,350 --> 00:05:46,680 the CO2 in the atmosphere is very small. 87 00:05:46,680 --> 00:05:49,960 In fact, if you put iron in one spot in 88 00:05:49,960 --> 00:05:54,910 the ocean models, you stimulate lots of production in that spot, 89 00:05:54,910 --> 00:06:03,030 although there are other nutrients like nitrogen and phosphorous 91 00:06:03,030 --> 00:06:06,800 in sea water that limit how much phytoplankton can grow, 92 00:06:06,800 --> 00:06:10,390 So by making one spot in a model that's very productive, you make a 93 00:06:10,390 --> 00:06:14,070 doughnut of areas around it that are less productive, 94 00:06:14,070 --> 00:06:15,380 and so it compensates. 95 00:06:15,380 --> 00:06:20,780 The impact on atmospheric CO2, according to the models, is low. 96 00:06:20,780 --> 00:06:24,890 And if it were actually done you wouldn't really be able to measure how much you're 97 00:06:24,890 --> 00:06:28,210 changing the CO2 concentration of the atmosphere. 98 00:06:28,210 --> 00:06:31,180 If you're looking to buy carbon offsets, 99 00:06:31,180 --> 00:06:34,670 the right to emit carbon by investing some money, 100 00:06:34,670 --> 00:06:39,010 and someone wants to sell you carbon offsets by grinding up old cars and 101 00:06:39,010 --> 00:06:42,260 putting them in the ocean, I would advise you to put your money elsewhere.